COMPOSITES SCIENCE AND TECHNOLOGY
·
2024
·
IF 8.3
Qi Sun,Kun Tian,Sihan Liu,Qing Zhu,Shuai Zheng,Jing Chen,Liping Wang,Si Cheng,Zhen Fan,Xupeng Fan,Dezhi Wang,Chunyan Qu,Changwei Liu
Low density aerogels with high fatigue resistance are widely used in the manufacturing of core material structures in aircraft fuselage to be able to tolerate the extreme environment of aerospace. However, most organic aerogel materials have poor energy absorption of external impact forces, and are prone to irreversible deformation , such as contracture and collapse in the process of long-term service. In order to solve this problem, a new type of thermosetting-thermoplastic polyimide composite aerogel was prepared, with its microstructure presenting the coexistence of the inner and outer skeletons. The intermolecular forces promoted the assembly of the soft thermoplastic layer and the strong thermosetting layer in the thermodynamic process with 4.63–6.55 μm range. The hard-soft layer structure improved the compressive and the shear load bearing capacities by bending of the panel (Compressive modulus is 1.60 MPa–3.52 MPa, tensile modulus is 1.04 MPa–1.45 MPa). Its permanent degradation less than 1.5 % after 500 cycles at 30 % strain. C–CPIAs also exhibited excellent heat resistance and thermal insulation performances, with a T 5% value of 612 °C (C-CPIA-2), T g of 458 °C (C-CPIA-3). The sandwich materials can be used as outer protective composite material of aircraft fuselage for future deep space missions .
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DOI
高影响因子
EUROPEAN POLYMER JOURNAL
·
2025
·
IF 6.3
Jie Liu,Jun Yang,Zijia Zhang,Qian Jiang,Lele Sun,Chaoyi Peng,Jin Wang,Li Xiang,Anlian Pan
In order to prepare polyimide materials with excellent optical transparency and UV barrier, the effects of the number and substitution position of −CF 3 groups on polyimide properties were investigated. Researchers synthesized four novel diamine monomers (BPA-O, BPA-NH 2 , BPAF-O, BPAF-NH 2 ) and synthesized eight high-performance colorless polyimides (PI-1 ∼ PI-8). On the one hand, the strong electron-withdrawing effect of −CF 3 restricts electron movement within the molecular chain, weakening the CTC effect of the molecular chain and thereby enhancing the transparency of the film. On the other hand, the ortho -substitution of −CF 3 on the imide ring induces greater twisting of molecular chains, disrupts their close packing, and thereby exerts a positive effect on enhancing the optical transparency of the film. The high bond energy of the C-F bond and the introduction of the flexible group −O- act as an “energy buffer,” suppressing UV-induced main chain breakage and achieving high UV barrier. All CPI films exhibit excellent transparency and thermal stability, with a cut-off wavelength range of 325 nm-381 nm and a transmittance range of 78.7 %-88 % at 550 nm. They have good optical properties, with T d5% distributed in the range of 511.5 °C − 533.7 °C, and the glass transition temperature ( T g ) distributed in the range of 197.3 °C-234.4 °C, demonstrating good thermal stability. Additionally, the cut-off wavelength is at a relatively high level, reaching up to 381 nm.
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DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2023
·
IF 5.2
Huijie Zhao,Kaiyue Han,Yang Li
Flexible humidity sensors show great potentials in the fields of smart apparels, biomedicine, human-machine interaction, etc., and they have attracted much attention in recent years. Herein, strip-type flexible capacitive humidity sensors (SFCHS) were facilely prepared by intertwining copper wires covered with soluble polyimide (PI) and poly(glycidyl methacrylate) (PGMA). The “pine nut” microstructure on copper wire surface and network structure between PGMA and PI strengthened the adhesion between the copper wire electrode and the polymeric sensitive materials, leading to better stability and sensing performance. The SFCHS with a double helix configuration showed good sensitivity (capacitance change of 111.5% between relative humidity (RH) of 11–98%), moderate hysteresis (∼6.6% RH) and fast response (t adsorption /t desorption : 10.1 s/5.2 s) at room temperature . Furthermore, the self-standing SFCHS revealed stable capacitance under bending and good long-term stability. In addition, the flexible sensor could monitor real-time change of water content in various liquids (transformer oil, hydraulic oil, ethanol and n-dodecane), suggesting potentials for detecting water content in liquids. The work provides references for developing advanced flexible capacitive humidity sensors for measuring moisture in both air and liquids.
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高影响因子
COMPOSITES PART B-ENGINEERING
·
2021
·
IF 9.078
Haitao Zhang,Xupeng Fan,Weijun Chen,Yubo Wang,Changwei Liu,Baojun Cui,Gang Li,Junjun Song,Daoxiang Zhao,Daming Wang,Liwei Zhao,Xiao Zhang,Huikang Xu,Chunhai Chen
Polyimide (PI) foams possess excellent mechanical properties, high-temperature resistance, and other unique properties, which facilitate impact in aerospace, automotive, and microelectronics industries. However, when they are used as lightweight insulation structural layers for high-temperature carbon fiber reinforced composites , improvement in thermal-insulating properties and temperature resistance of PI foams without compromising the flexibility in extreme environments is a challenging task. In this study, the flexible blocks were linked into rigid polymeric structures to fabricate a thermoplastic structure through a simple aqueous strategy to construct hydrogen-bonding networks. Thus, with a low shrinkage of 8.42%, an ultrahigh compressive modulus of 11.17 MPa, and a specific modulus of 81.03 MPa cm 3 g −1 was successfully achieved. Benefitting from the formation of ultra-strong network backbones, foams showed excellent thermal-insulating properties and temperature resistance. The robust porous material with thermal-insulating properties (0.0481 W m −1 K −1 ) exhibited a compression modulus of 4.21 MPa after heat treatment at 300 °C and maintained 91% strength retention, thus it can be used as lightweight heat-insulation composite sandwich structures up to 300 °C. The copolymer foam obtained by using 30 mol% flexible blocks reserves its high flexibility undergoing only 10% dimensional changes after 40,000 compression-release cycles. The lightweight thermoplastic PI foams with flexibility, thermal-insulating properties, and temperature resistance can be used for high-temperature lightweight composite sandwich structures in aeronautics and space exploration.
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高影响因子
RSC Advances
·
2016
·Vol. 6
·期 109
·107533-107541
·
IF 3.289
Xinliang Fang,Shanfeng Wang,Yanxiao Li,Xiaoyun Liu,Xinxin Li,Shaoliang Lin,Zhong-Kai Cui,Qixin Zhuang
Novel Fe3O4/polyimide (PI) composite films with extraordinary dielectric properties were prepared via in situ polymerization of PI in the presence of 4,4′-diaminodiphenyl ether (ODA), pyromellitic dianhydride (PMDA) and compatible amine-functionalized carbon-coated Fe3O4 nanoparticles (Fe3O4@C–NH2). Fe3O4 nanoparticles prepared via solvothermal reaction were coated with crosslinked glucose and then surface-grafted via carbodiimide coupling. The core–shell structure of Fe3O4@C–NH2 was thereafter obtained with amine functionalities on the carbonized-glucose shell. Homogeneous dispersion of Fe3O4@C–NH2 and strong interfacial covalent bonding on the shell surface contributed to high dielectric constants (ε) and extremely low dielectric losses (tan δ) in the composite films. The highest dielectric constant of the composite films was 58.6 at 1 kHz when the Fe3O4@C–NH2 composition was 1.13 vol%, as well as a low dielectric loss of 0.0091 and a high breakdown strength of 126.5 ± 11.3 MV m−1 were observed without considerable sacrifice of the thermal stability and mechanical properties.
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高影响因子
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
·
2025
·
IF 8.9
Xi Chen,Yu Zhang,Yue Qiao,Enmao Zhang,Wenqi Zhao,Xigao Jian,Cheng Liu
Carbon fiber-reinforced high-performance thermoplastic polymer (CFRHPTP) composites are highly susceptible to interlaminar damage when are subjected to external damage, which affects their mechanical properties and structural integrity. In this study, a core–shell electrospun fiber with partially exposed carbon nanotubes (CNTs) on the shell layer was prepared by coaxial electrostatic spinning of polyimide/polyvinylpyrrolidone (PI/PVP) core–shell fiber veils containing CNTs, and then was gradually etched until the CNTs embedded in the shell layer of the fibers were as gradually exposed. The introduction of core–shell veils with micro–nanostructures into the interlayers of carbon fiber-reinforced poly(phthalazinone ether sulfone ketone) (CF/PPESK) composites enhanced their interlayer and in-plane properties. The initial and propagation values of the composite’s mode I interlaminar fracture toughness were increased to 1182 J/m 2 and 1266 J/m 2 (46 % and 39 % increases, respectively), and the mode II interlaminar fracture toughness was improved to 2091 J/m 2 (113 % increase) after the introduction of electrospun veils into the interlayers. In addition, the tensile strength, flexural strength, and interlaminar shear strength of the CF/PPESK composites were enhanced by 17 %, 20 %, and 18 %, respectively. Molecular dynamics simulations elucidated the positive effect of PVP for an enhanced interface between the spun fiber and resin. Simultaneous increases in toughness and strength of the CF/PPESK composites were achieved. This study provides new ideas and methods for synergistic reinforcement and toughening of CFRHPTP composites through interlayer design of high-performance composites.
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高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2021
·
IF 8.742
Chenjie Wei,Rongrong Qiang,Ligang Lin,Yixin Gao,Shuyan Ma,Xihang Zhang,Xiaojun Huang
Desalination of brackish water and purification of drinking water still pose several challenges. Combination of in-situ hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in polyamic acid (PAA) solution along with imidization reaction provide a novel polyimide/SiO 2 (PI/SiO 2 ) membrane. This is the first synthesis of a PI nanofiltration (NF) membrane with three-dimensional (3D) water channels, ultra-thin skin layer (30 ± 2 nm), and high flux at low operating pressure, by one-step phase inversion method. There was no additional requirement of an acid, since PAA served as a catalyst. The SiO 2 cross-linked network provided the skeletal support, due to hydrogen bonding between PAA-PI and silicon hydroxyl groups. The fabricated PI/SiO 2 membrane demonstrated a water contact angle of 45°, pore size of 1.05 ± 0.15 nm, Zeta potential of −30 mV, and tensile strength of 2.24 MPa when under optimized conditions. The loose PI/SiO 2 NF membrane exhibited salt rejection in the sequence of Na 2 SO 4 (87%)>MgSO 4 (67%)>NaCl (41%)>MgCl 2 (37%), which was consistent with size exclusion and Donnan exclusion effects. In particular, the water flux of 20.4 L/(m 2 h bar) was about 4–15 times higher than that of universal PI-NF membranes. The membrane also exhibited excellent stability for over six days when used for separation. Furthermore, the membrane showed excellent dye (Rose Bengal (RB), Brilliant Blue G (BBG), Amido Black (AB)) rejection of over 90%. To conclude, this work paves a new pathway for the fabrication of PI-NF membranes for efficient NF separation.
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高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2021
·Vol. 138
·期 42
·51233
·
IF 3.125
Jiali Xu,Li Yuan,Guozheng Liang,Aijuan Gu
It is still a challenge for simultaneously achieving high heat resistance, high strength and outstanding electrochemical performance for separators in power lithium-ion battery (PLB). Herein, new high performance electrospun separators are developed through building unique structure based on polyimide (PI) and poly (m-phenylene isophthalamide) (PMIA). Orthogonal tests (4 4 ) show that the magnitude order of electrospinning factors on the morphology of membrane is concentration>injection rate>receiving distance>voltage. With the optimum factors, the electrospun membrane (PI/PMIA) was prepared, which was further pressed at 100°C for 10 min to get treated membrane (H-PI/PMIA). Interestingly, the comprehensive performance of PI/PMIA is not a simple combination of those of PI and PMIA; instead, PI/PMIA has much better thermal and mechanical properties than both PI and PMIA, proving that PI/PMIA has a synergistic effect. PI/PMIA and H-PI/PMIA not only have good ionic conductivity and electrochemical stability, but also have superiorly high properties including dimensional stability (thermal shrinkage temperature>300°C), tensile strengths (24.1 MPa for PI/PMIA, 34.3 MPa for H-PI/PMIA) and capacity retentions (97.9%, 99.2%) compared with electrospun membranes for PLBs reported in the literature so far (SCI database). The mechanism behind these attractive performances is discussed from condensed structure of membranes.
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高影响因子
危险品化学品经营许可证（带存储）